Wikipedia
Pucadelphys
Pucadelphys andinus is an extinct non- marsupial metatherian species.
Fossils of Pucadelphys have been found at Tiupampa ( Bolivia).
It is small and likely to have eaten insects. It had a long tail, although incomplete on the best preserved fossils. It is possible that the tail was longer than (or at least as long as) its body. 17 vertebrae were preserved, and its estimated that there was 5 to 10 additional vertebrae originally.
It is regarded as partially arboreal, and partially terrestrial.